/*
 * File:	Random.cpp
 *
 * Copyright (c) Freescale Semiconductor, Inc. All rights reserved.
 * See included license file for license details.
 */

#include "Random.h"
#include <stdexcept>

#ifdef WIN32
#ifndef _WIN32_WINNT
#define _WIN32_WINNT 0x0400
#endif
#include <windows.h>
#include <wincrypt.h>
#else // WIN32
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#endif // WIN32

#ifdef WIN32

MicrosoftCryptoProvider::MicrosoftCryptoProvider()
{
    if (!CryptAcquireContext(&m_hProvider, 0, 0, PROV_RSA_FULL, CRYPT_VERIFYCONTEXT))
    {
        throw std::runtime_error("CryptAcquireContext");
    }
}

MicrosoftCryptoProvider::~MicrosoftCryptoProvider()
{
    CryptReleaseContext(m_hProvider, 0);
}

#endif // WIN32

RandomNumberGenerator::RandomNumberGenerator()
{
#ifndef WIN32
    m_fd = open("/dev/urandom", O_RDONLY);
    if (m_fd == -1)
    {
        throw std::runtime_error("open /dev/urandom");
    }
#endif // WIN32
}

RandomNumberGenerator::~RandomNumberGenerator()
{
#ifndef WIN32
    close(m_fd);
#endif // WIN32
}

uint8_t RandomNumberGenerator::generateByte()
{
    uint8_t result;
    generateBlock(&result, 1);
    return result;
}

void RandomNumberGenerator::generateBlock(uint8_t *output, unsigned count)
{
#ifdef WIN32
#ifdef WORKAROUND_MS_BUG_Q258000
    static MicrosoftCryptoProvider m_provider;
#endif
    if (!CryptGenRandom(m_provider.GetProviderHandle(), count, output))
    {
        throw std::runtime_error("CryptGenRandom");
    }
#else  // WIN32
    if (read(m_fd, output, count) != count)
    {
        throw std::runtime_error("read /dev/urandom");
    }
#endif // WIN32
}
